Chapter 3
Audio Tool
Overview
The Audio Tool enables Communique! users to use vocal communication during conferences. The Audio Tool provides users with high quality, low latency audio, and supports multicast routing to reduce network bandwidth consumption. A limited version of the Plugin, Audio Tool Lite, is bundled with the Communique! Lite package. Audio tool Lite can receive audio but cannot send it.
This chapter covers
- the Audio Tool at a glance—basic controls
- checking your audio equipment
- using the Audio Tool in a conference
- features for fine-tuning audio
- preserving your configuration
- leaving the tool’s control panel
- a selectable network data transport mechanism
The Audio Tool at a Glance
The Control Panel
Clicking the Audio Tool’s icon in the Conference Manager brings up the Audio Tool’s control panel.
Three basic controls are available:
- Receiving Volume
- Sending Volume (disabled for Audio Tool Lite)
- Mute (disabled for Audio Tool Lite
By default, you both send and receive audio when a conference begins with Communique!; Communique! Lite packages receive audio.
Controls that allow further fine tuning and configuration are available from the Audio Tool’s pulldown menus.
- Audio
- Options
- Help
Playback Volume
This control regulates the sound level coming from other conference participants. Its value can range from 0 (off) to 100. There are three ways Playback Volume can be adjusted.
- Drag the Playback Volume slider to the left to decrease volume, and to the right to increase volume.
- Click on either side of the slider control, which decreases or increases the value by 10, respectively.
- Enter a specific value in the box to the left of the slider.
Entering a value less than 0 or greater than 100 results in the volume being set to 0 or 100, respectively.
The factory default value for the Playback Volume is 50.
Sending Volume
This control regulates the sound level going to other conference members; it is adjusted in the same manner as the Playback Volume control.
The factory default value for Sending Volume is 50.
Mute
The Mute control stops the Audio Tool from sending audio to other conference members. Like the Mute button on a telephone, when this button is selected, no one in the conference will hear you speak.
When Mute is active, the button will be shaded. Click on the button to toggle the Mute between On and Off.
Menus
In addition to the three basic controls, there are three pulldown menus available.
- Audio
- Options
- Help
The Audio menu provides the ability to save and recall the settings for the Audio Tool’s controls, launch the AudioScope, and close the Audio Tool.
The Options menu enables you to load the Devices dialog, the Members dialog, the Audio Tool’s Advanced controls, and the Networking information panel.
The Help menu accesses the online information.
The Status Bar
At the bottom of the Audio Tool’s main panel is a status bar. At the right end of the bar your user address is displayed. The left end of the bar displays messages and control hints.
Control hints are brief messages stating the use of a control currently under the mouse pointer. For example, moving the mouse to the Mute button displays the hint, "Mute (unmute) sending audio".
Checking Your Audio Equipment
Making Connections
Before starting or joining a conference, you should ensure that your audio input and output devices are properly connected, powered and working.
- The microphone should be plugged in to your workstation’s microphone input jack.
- The microphone should have the appropriate power source. Some microphones are self-powered, and others draw power from the workstation. (MDL’s microphones are self-powered.)
- External speakers should be connected to the appropriate audio output jack (line-out or headphones).
You do not need a microphone for the Communique! Lite package.
Telling Communique! About Your Equipment
If you are using nonstandard audio equipment—such as headphones for output instead of external speakers, or a VCR for input rather than a microphone—check the appropriate settings in the Audio Tool’s Devices dialog box available under the Options menu
Line-Level vs. Microphone-Level
Most audio devices can be classified as producing either a microphone-level or a line-level output signal. A microphone-level signal is one which is essentially non-amplified, producing output levels of less than 1 millivolt. Most microphones produce a microphone-level output signal. VCR’s typically produce line-level output signals. Line-level signals typically produce output levels up to 1 volt.
When connecting audio equipment to your workstation, you need to select the correct input port based on the device’s type of output signal. Most workstations offer both microphone-in and line-in jacks.
Connecting a microphone to a line-in jack or a VCR to a microphone-in jack produces distorted or nonexistent audio from Communique!, and could potentially damage your equipment.
Using the Local Monitor
The Audio Tool has a Local Monitor feature which allows you to hear yourself as you actually sound to other conference participants. The Local Monitor can be used to test your audio equipment, and to make sure that your sending volume is set properly.
Using the Audio Tool in a Conference
Autostart Audio
Once you join a conference, the Audio Tool is automatically active. When the conference starts, you will be sending audio and receiving it from other members. You should be able to hear all conference members speak. Additionally, all conference participants should be able hear you (unless you are using Communique! Lite).
This behavior is governed by the Audio Tool’s Preferences, available from the Options menu. You can choose whether you wish to automatically send or receive audio upon joining a conference.
You can select those conference members who you wish to transmit audio to and receive audio from using the Members dialog, available from the Options menu.
Adjusting Volume Levels
If the sound coming from all conference participants is too soft or too loud, increase or decrease your Playback Volume respectively. However, if a single conference member is too loud or soft when everyone one else sounds fine, ask that person to adjust his or her Sending Volume until it conforms with that of the other conference members.
On the other hand, if other conference participants complain that you sound either too soft or too loud, you should adjust your Sending Volume appropriately.
If your Sending Volume is set at 100 and you still sound quiet to other conference members, you may need to speak closer to the microphone. (On a self-powered microphone this behavior may indicate a weak battery.)
If your audio sounds distorted to other conference members, you may be speaking too close to the microphone.
The Audio Scope
The AudioScope is a simple but handy tool that provides an audio meter as well as a list of audio conference participants. A small speaker symbol appears beside the names of conference participants who are currently speaking. The audio meter shows the level of audio your microphone is picking up (the green bar graph) and the current Silence Sensor level you have set (the red line). Whenever the current audio level that your microphone picks up exceeds the Silence Sensor setting, the word "Talking" will appear, indicating that you are transmitting audio.
The AudioScope is started from the Audio menu in the Audio Tool’s control panel. It is dismissed by clicking the OK button.
Features for Fine-Tuning the Audio Tool
The Options Menu
The Options menu provides access to the controls of the Audio Tool. With these controls you can select which users will receive your audio, and you can select which users you wish to receive audio from. Other features allow you to customize the Audio Tool’s performance and sensitivity for your particular environment.
Selecting any of the five choices—Devices, Members, Advanced, Network, or Preferences—in the Options menu brings up a dialog box. At the bottom of each are OK, Cancel, and Help buttons. An Apply button may also be present in some dialogs.
OK—Closes the dialog box and stores the new settings.
Cancel—Closes the dialog box and dismisses any changes.
Help—Opens the help viewer appropriate to the dialog box.
Apply—If present, stores the new settings without dismissing the dialog box.
Devices—Your Equipment at Work
Choosing Your Input and Output Devices
Although a microphone is the most commonly used audio input device and external speakers are the most common for output, alternatives exist and the Audio Tool provides for their use.
For instance, if you are playing a videotape in your conference, you would need to use the audio output of your VCR/VCP/VDP as input.
1. Choose Device from the Options menu in the Audio Tool’s control panel.
The Device dialog box appears.
2. Choose the line-in icon (a circle with an arrow pointing to its center) on the Input line.
3. Click OK.
If you wish, you can use a pair of headphones as your audio output device rather than using external speakers. In order to select headphones:
1. Choose Device from the Options menu in the Audio Tool’s control panel.
2. Choose the icon representing a pair of headphones on the Output line.
3. Click OK.
The default devices for Communique!’s use are microphone for input and external speakers for output. Available input devices are microphone and any device generating a signal suitable to a line-in jack. Available output devices are speakers, headphones, and any device driven by a line-out signal.
You can use the MDL Call Port, which includes an external speaker, a high quality microphone, and advanced echo cancellation technology. The Call Port comes with a set of Line-in/Line-out cables, and a set of Microphone/Headphone cables. You should use the set of cables that corresponds to the available ports on your workstation.
Local Monitor
From the Device dialog you can also turn on the Local Monitor. The Local Monitor sends the audio signal coming from the selected input source to the specified output device. By turning on the Local Monitor you not only verify your device selection, but you can also check your signal strength and quality.
The Local Monitor is controlled by means of a check box. Clicking the box toggles its state.
1. Select Device from the Options menu.
2. Click the Local Monitor box to activate the feature.
3. Adjust Sending Volume so that you hear yourself and create no signal feedback (a high-pitched squeal).
4. Click the Local Monitor box to deactivate it once the audio level is satisfactory.
5. Click OK to close the Device dialogue box.
If after turning on the Local Monitor you cannot hear your audio, or the signal sounds corrupted, check your device selections in the Devices dialog.
Members—Selective listening and Private Conversations
With the Members dialog, available from the Options menu, you have the ability to choose exactly who in the conference may receive your audio and specify to whom you will listen.
The Members dialog box holds two lists of conference participants: those members eligible to receive your audio and those members whose audio you will receive.
Highlighting names in the "Offer Audio To" list determines who can receive your audio.
1. Bring up the Members dialog from the Options menu.
2. Click on members’ names to toggle their selection—either on or off—until only those you wish to hear your audio are highlighted.
Two shortcuts for selecting members of your audio conference are the Everybody and Nobody buttons. They highlight everyone or deselect all conference participants respectively.
3. Click on the Apply button to implement the change.
You could also click the OK button to confirm your choices, but this also dismisses the Members dialog box.
On the other hand, choosing names in the "Accept Audio From" list specifies whose audio you receive.
1. With the Members dialog open, toggle the selection of names appropriately.
The Everybody and Nobody buttons work here as they do for the "Offer Audio To" list, selecting and deselecting the entire list of conference members.
2. Click OK.
Once the OK button is clicked, any changes will take effect and the dialog box will be dismissed.
Advanced settings—Getting It Just Right
The Advanced settings dialog box contains controls for the audio parameters that are changed infrequently: Silence Sensor, Compression, Echo Cancellation, and A/V Sync.
With the exception of Compression (a control switched either on or off), all of Advanced controls are sliders representing a range of values from 0 to a maximum of 100.
There are three ways to set the value of a slider.
- Drag the slider to the left to lower its setting, or to the right to increase it.
- Click to the left of the slider to decrement the value by 10 and to the right to increment the value.
- Enter a specific value in the box to the left of the slider.
Entering a value less than 0 or greater than 100 results in the volume being set to 0 or 100, respectively.
Modified values in the Advanced dialog box take effect immediately, except for Compression, which remains unchanged while audio is active.
Silence Sensor
The Silence Sensor reduces audio traffic and increases quality by filtering low-level background noise. When audio picked up by the microphone falls below the Silence Sensor’s level, no audio is transmitted to the conference. The Silence Sensor prevents useless audio traffic from consuming network resources.
The Silence Sensor usually needs adjustment during the initial equipment set-up due to significant variations in environment and microphone sensitivity. A good setting allows for the clear broadcast of audio when you speak yet no traffic when you are silent.
If other conference members constantly hear a great deal of ambient noise coming from you including the sound of your own speaker (creating an echo), you need to raise the level of your Silence Sensor.
If, on the other hand, the signal others hear from you is choppy and broken up, you should reduce the Silence Sensor’s value.
The Audio Scope can also be used to help set your Silence Sensor correctly. The red line on the meter indicates your current Silence Sensor setting. When you are in a conference and are not speaking, the green bar graph indicates the ambient noise level. You should adjust your Silence Sensor so that it rests just beyond the ambient noise level.
If other conference members hear a great deal of ambient noise coming from your Audio Tool, you should raise the level of the Silence Sensor until you see the "Talking" message only when you begin speaking.
Compression
Using compression, the Audio Tool has the ability to reduce audio traffic by half. On a congested network, compression can result in a performance improvement for other network activities. The tradeoff, however, is reduced audio quality.
Compression is toggled on or off by means of a check box in the Advanced dialog box.
If the network on which you are conferencing becomes heavily loaded, you may wish to use audio compression.
1. Open the Advanced dialog box for the Audio Tool from the Options menu in the tool’s control panel.
2. Click the Compression check box.
3. Click OK to dismiss the dialog box.
4. Stop sending audio, including to the Local Monitor.
5. Begin sending audio by selecting conference members to receive your signal.
To avoid conflicts in audio, the Audio Compression setting can not be changed while in a conference.
The PC version of Communique! cannot currently receive compressed audio.
Echo Cancellation
Stations using Communique! typically have both microphones and speakers. The close proximity of these devices can create a situation in which the audio received on the speakers is picked up by the microphone and rebroadcast out to the conference. This effect is called an echo and is reduced by the Echo Cancellation control.
1. Open the Advanced dialog box.
2. Increase the Echo Cancellation’s value until conference participants no longer hear their own audio being retransmitted.
When set too high, Echo Cancellation causes Communique! to ignore what you say immediately after receiving another’s audio. Too high a value can also distort your audio.
3. Click the OK button in the Advanced dialog box.
Users with the MDL Call Port can turn off echo cancellation, because the Call Port’s hardware automatically eliminates echo from the audio signal using digital signal processing technology.
A/V Sync
Communique! sends audio and video in distinct data streams across the network, thereby creating a small amount of latency between the two signals. A/V Sync attempts to reduce this behavior by tying incoming audio to the incoming video.
Although a high association between audio and video is always desirable, excessive network delays can cause packets of either audio or video to be dropped in an effort to maintain synchronization. Dropped information can create jerky video playback or skips in the audio. The A/V Sync value should be reduced to minimize these signal irregularities.
1. Open the Advanced dialog box under Options in the Audio Tool.
2. Begin decreasing the A/V Sync value until an acceptable combination of smooth playback and synchronization is found.
3. Click OK to dismiss the Advanced dialog box.
Networking
Preferred Transport
The Audio Tool supports Multicast UDP or Unicast UDP network transport. This field indicates which network transport protocol is being used by the Audio Tool. Your network transport protocol is set internally by a Communique! initialization file. For details on changing it, consult the Communique! Administrator’s Guide.
Unicast is the traditional IP transport protocol. Under Unicast, one stream of data is sent over the network to every user who is receiving your audio. For example, under Unicast, a person sending audio to five other conference members will send out five separate streams, one to each individual user.
Multicast, on the other hand, sends only one stream of data, which is automatically received by every user it is intended for. In multipoint conferences, multicast greatly reduces the amount of network resources used by audio, and decreases the workload of the sending machine. If multicast is selected as your Preferred Transport, Communique! will still automatically detect which users are using unicast and automatically send them an individual stream.
Before using multicast, you should make sure that all of the network hardware you use supports multicast routing, including routers, network cards, and hubs.
Multicast Range
Multicast Range is an attribute of Multicast routing that defines how far a multicast packet travels across the network. Each time a multicast packet travels through a network gateway, its TTL value is decremented. Although there are no set standards for Multicast Range, there are a few conventions that have been established.
1 Restrict the packets to the local subnet
32 Restrict the packets to the site
64 Restrict the packets to the region
128 Restrict the packets to the continent
256 Do not restrict the packet’s travel at all
You should have the Multicast Range set to the lowest amount required. Multicast Range is set internally by a Communique! initialization file. For information on changing it consult the Communique! Administrator’s Guide.
If you are using Multicast UDP as your video transport mechanism and a conference member’s host station operates farther away (across more gateways) than the Multicast Range setting allows, that conference member will not receive your video.
Preferences
The Preferences dialog defines the default behavior of the Audio Tool for accepting and sending audio at the beginning of a conference. The Audio Tool ships with the default behavior of accepting audio from everyone and sending audio to all conference members.
Sending
You can have audio sending turned off at the beginning of any conference.
1. Bring up Preferences from the Options menu.
2. Click Nobody on the "Offer Audio To" line.
3. Click the OK button.
Receiving
Further, with the Audio Tool’s Preferences you can automatically refuse all other audio in a conference.
1. Bring up Preferences from the Options menu.
2. Click Nobody on the "Accept Audio From" line.
3. Click the OK button.
Note that any changes made in the Members dialog during a conference override these Preference settings for the duration of the current conference.
Preserving Your Configuration and Monitoring with AudioScope
Saving Current Settings—When Everything Is Just Right
Once you have suitably configured the Audio Tool, you will want to save the settings for future use. In order to store your current settings on disk, select Save from the Audio menu.
The next time you use the Audio Tool, your current settings will be used. Also if you change your settings, you can recall the saved set by selecting Load from the Audio menu in the control panel.
If you do not save your settings, the next time Communique! is started the Audio Tool’s last saved set will be loaded.
The default settings shipped with Communique! are always available by choosing Factory from the control panel’s Audio menu.
Leaving the Audio Tool Control Panel
All Finished
Once you have correctly configured your Audio Tool settings and saved them, you can leave the Audio Tool’s control panel. Selecting Close from the control panel’s Audio menu will dismiss the window.
Closing the Audio Tool does not disable audio in a conference, and the audio configuration is not lost when the tool is closed.